how to prevent "directory already exists error" in a makefile when using mkdir

makefile directory exists
KPexEA picture KPexEA · Sep 19, 2008 · Viewed 113.7k times · Source

I need to generate a directory in my makefile and I would like to not get the "directory already exists error" over and over even though I can easily ignore it.

I mainly use mingw/msys but would like something that works across other shells/systems too.

I tried this but it didn't work, any ideas?

ifeq (,$(findstring $(OBJDIR),$(wildcard $(OBJDIR) )))
-mkdir $(OBJDIR)
endif

Answer

ofavre picture ofavre · May 29, 2011

Looking at the official make documentation, here is a good way to do it:

OBJDIR := objdir
OBJS := $(addprefix $(OBJDIR)/,foo.o bar.o baz.o)

$(OBJDIR)/%.o : %.c
    $(COMPILE.c) $(OUTPUT_OPTION) $<

all: $(OBJS)

$(OBJS): | $(OBJDIR)

$(OBJDIR):
    mkdir -p $(OBJDIR)

You should see here the usage of the | pipe operator, defining an order only prerequisite. Meaning that the $(OBJDIR) target should be existent (instead of more recent) in order to build the current target.

Note that I used mkdir -p. The -p flag was added compared to the example of the docs. See other answers for another alternative.

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